Adds Expected Delivery Time meta box in WooCommerce Product page Shipping options

bh_expected_delivery_time.php

<?php

// Save in your child theme and add in your functions.php:
// require_once('bh_expected_delivery_time.php');


add_action( 'woocommerce_product_options_shipping', 'bh_expected_delivery_time_field' );
function bh_expected_delivery_time_field() {
    // Print a custom text field
    woocommerce_wp_text_input( array(
        'id' => '_bh_expected_delivery_time',
        'label' => 'Expected delivery time',
        'description' => 'Estimated shipping time in days. To be displayed, separately, prominently from the main description.',
        'desc_tip' => 'true',
        'placeholder' => 'Days'
    ) );
}
add_action( 'woocommerce_process_product_meta', 'bh_expected_delivery_time_save_field' );
function bh_expected_delivery_time_save_field( $post_id ) {
    if ( ! empty( $_POST['_bh_expected_delivery_time'] ) ) {
        update_post_meta( $post_id, '_bh_expected_delivery_time', esc_attr( $_POST['_bh_expected_delivery_time'] ) );
    }
}
add_shortcode('expected_delivery_time', 'bh_expected_delivery_time');
function bh_expected_delivery_time( $atts = array() ) {
		
	if( is_int( $atts ) )
		$post_id = $atts;
	elseif( is_array( $atts ) && array_key_exists( $atts, 'post_id' ) )
		$post_id = $atts['post_id'];
	else
		$post_id = get_the_ID();
	
    $expected_delivery_time_meta = get_post_meta($post_id, '_bh_expected_delivery_time', true);
    return $expected_delivery_time_meta;
}

// Use in visual editor:
// [expected_delivery_time]
// [expected_delivery_time post_id=123]

// Use in theme:
// echo bh_expected_delivery_time();
// echo bh_expected_delivery_time( 123 );